A takkanah (plural takkanot) is a major legislative enactment within halakha (Jewish law), the normative system of Judaism's laws.
A takkanah is an enactment which (1) revises an ordinance that no longer satisfies the requirements of the times or circumstances, or which (2), being deduced from a Biblical passage, may be regarded as new. It is, therefore, the antithesis of the Gezerah. Takkanot were framed even in the time of the Second Temple in Jerusalem, those of unknown origin being ascribed to earlier leaders, and they have been promulgated at all subsequent periods of Jewish history. The term is applied also to the institution provided for in the enactment.
Read more about Takkanah: Introduction, Early Biblical Takkanot, Takkanot Ascribed To The Men of The Great Assembly, Takkanot of Johanan Ben Zakkai, Ordinance Ascribed To Gamaliel II. and The Court of Jabneh, Ordinances of The Last Tannaim, Takkanot For The Sake of Peace, Order and Fair Business, Business Takkanot, Other Ordinances Dating From The Mishnaic Period, Post-Mishnaic Ordinances, In Conservative Judaism